There is in the field of high pulse repetition rate laser system, e.g., an excimer or molecular fluorine gas discharge laser system, useful for surface treatment of a material on a panel having a substrate covered with one or more layers, including an upper layer of amorphous silicon, to be melted and recrystallized into an elongated poly-crystalline form of silicon, e.g., for the subsequent formation of thin film transistors for making products such as flat panel displays a need for better system control, which applicants address. Such systems may be utilized, e.g., for low temperature polysilicon processes (“LTPS”) or thin beam sequential lateral solidification (“tbSLS”) systems.